import pygame,sys,random,time
from pygame.locals import *   #从pygame模块导入常用的函数和常量
#定义颜色变量
black_colour = pygame.Color(0,0,0)
white_colour = pygame.Color(255,255,255)
red_colour = pygame.Color(255,0,0)
grey_colour = pygame.Color(150,150,150)
#定义游戏结束函数
def GameOver(gamesurface):
    #设置提示字体的格式
    GameOver_font = pygame.font.SysFont("MicrosoftYaHei", 16)
    #设置提示字体的颜色
    GameOver_colour = GameOver_font.render('Game Over',True,grey_colour)
    #设置提示位置
    GameOver_location = GameOver_colour.get_rect()
    GameOver_location.midtop = (320,10)
    #绑定以上设置到句柄
    gamesurface.blit(GameOver_colour,GameOver_location)
    #提示运行信息
    pygame.display.flip()
    #休眠5秒
    time.sleep(5)
    #退出游戏
    pygame.quit()
    #退出程序
    sys.exit()
#定义主函数
def main():
    #初始化pygame，为使用硬件做准备
    pygame.init()
    pygame.time.Clock()
    ftpsClock = pygame.time.Clock()
    #创建一个窗口
    gamesurface = pygame.display.set_mode((640,480))
    #设置窗口的标题
    pygame.display.set_caption('tanchishe snake')
    #初始化变量
    #初始化贪吃蛇的起始位置
    snakeposition = [100,100]
    #初始化贪吃蛇的长度
    snakelength = [[100,100],[80,100],[60,100]]
    #初始化目标方块的位置
    square_purpose = [300,300]
    #初始化一个数来判断目标方块是否存在
    square_position = 1
    #初始化方向，用来使贪吃蛇移动
    derection = "right"
    change_derection = derection
    #进行游戏主循环
    while True:
        #检测按键等pygame事件
        for event in pygame.event.get():
            if event.type==QUIT:
                #接收到退出事件后，退出程序
                pygame.quit()
                sys.exit()
            elif event.type==KEYDOWN:
                #判断键盘事件,用w,s,a,d来表示上下左右
                if event.key==K_RIGHT or event.key==ord('k'):
                    change_derection = "right"
                if event.key==K_LEFT or event.key==ord('j'):
                    change_derection = "left"
                if event.key==K_UP or event.key==ord('h'):
                    change_derection = "up"
                if event.key==K_DOWN or event.key==ord('l'):
                    change_derection = "down"
                if event.key==K_ESCAPE:
                    pygame.event.post(pygame.event.Event(QUIT))
        #判断移动的方向是否相反
        if change_derection =='left'and not derection =='right':
            derection = change_derection
        if change_derection =='right'and not derection =='left':
            derection = change_derection
        if change_derection == 'up' and not derection =='down':
            derection = change_derection
        if change_derection == 'down' and not derection == 'up':
            derection = change_derection
        #根据方向，改变坐标
        if derection == 'left':
            snakeposition[0] -= 20
        if derection == 'right':
            snakeposition[0] += 20
        if derection == 'up':
            snakeposition[1] -= 20
        if derection == 'down':
            snakeposition[1] += 20
        #增加蛇的长度
        snakelength.insert(0,list(snakeposition))
        #判断是否吃掉目标方块
        if snakeposition[0]==square_purpose[0] and snakeposition[1]==square_purpose[1]:
            square_position = 0
        else:
            snakelength.pop()
        #重新生成目标方块
        if square_position ==0:
            #随机生成x,y,扩大二十倍，在窗口范围内
            x = random.randrange(1,32)
            y = random.randrange(1,24)
            square_purpose = [int(x*20),int(y*20)]
            square_position = 1
        #绘制pygame显示层
        gamesurface.fill(black_colour)
        for position in snakelength:
            pygame.draw.rect(gamesurface,white_colour,Rect(position[0],position[1],20,20))
            pygame.draw.rect(gamesurface,red_colour,Rect(square_purpose[0],square_purpose[1],20,20))
        #刷新pygame显示层
        pygame.display.flip()
        #判断是否死亡
        if snakeposition[0]<0 or snakeposition[0]>620:
            GameOver(gamesurface)
        if snakeposition[1]<0 or snakeposition[1]>460:
            GameOver(gamesurface)
        for snakebody in snakelength[1:]:
            if snakeposition[0]==snakebody[0] and snakeposition[1]==snakebody[1]:
                GameOver(gamesurface)
        #控制游戏速度
        ftpsClock.tick(5)

if __name__ == "__main__":
    main()

